You have to be Christian to truly be American? Many people in the U.S. say so.

About one-third of all Americans think that you have to be a Christian to truly be an American — despite the history of religious liberty that dates back to the nation’s very earliest days.

In a timely survey released Wednesday afternoon, just as the United States is debating the merits of suspending immigration from seven majority-Muslim countries, the Pew Research Center asked residents of numerous nations what it takes to truly belong in their countries. Americans were far more likely than residents of other countries included in the survey to say that religion was key to sharing in the national identity.

Thirty-two percent of Americans said one should be Christian to really be American, compared to just 13 percent of Australians, 15 percent of Canadians and 15 percent of Europeans who felt the same way about belonging in their homelands.

The same number of Americans — 32 percent — said that being born in the United States is key to being an American. More Americans — 45 percent — said that sharing “national customs and traditions” was important, and many more — 70 percent — said being an American meant speaking English.

Religion was the only question on which Americans were an outlier. On birth, language and customs, America fell in line with other industrialized nations.

While religious minorities have lived in the United States since before the American Revolution — Thomas Jefferson defended the rights of Muslims, and George Washington wrote a famous letter guaranteeing religious liberty to the Jews of Rhode Island — still pastors and politicians alike have frequently described the United States as a “Christian nation.”

Republicans, who are themselves more likely to be Christian, said at a higher rate that one need be Christian to be American: 43 percent compared to 29 percent of Democrats and 26 percent of independents.

One’s own religion also strongly affected the answers: Pew found that 57 percent of white evangelical Protestants thought it was very important to be Christian in order to be American, while 29 percent of white mainline Protestants, 27 percent of Catholics and just 9 percent of people unaffiliated with a faith felt the same way.

This opinion is apparently becoming much less popular with the younger generation of Americans, who are less likely to affiliate with a religion than generations before them. Among adults over 50, 44 percent told Pew that being Christian was key to being American; among those younger than 35, 18 percent said so.

In Sweden, where 73 percent of the population is Protestant but many do not consider religion important in their lives, a mere 7 percent of respondents felt that one needs to be Christian to be a real Swede. The number was similarly low in several other European countries: 8 percent in the Netherlands, 9 percent in Spain, 10 percent in France and 11 percent in Germany.